3-aryl substituted pyrazolo 4,3-d!pyrimidine derivatives; corticotropin-releasing factor receptor (CRF1) specific ligands

ABSTRACT

This invention encompasses compounds of the formula ##STR1## wherein Ar represents a mono-, di- or trisubstituted aryl group where at least one position on Ar ortho to the point of attachment to the pyrazole ring is substituted; and 
     R 1  represents lower alkyl; 
     R 2  is hydrogen or lower alkyl; and 
     R 3  and R 4  independently represent organic and inorganic substituents, 
     which compounds are highly selective partial agonists or antagonists at human CRF 1  receptors and are useful in the diagnosis and treatment of treating stress related disorders such as post traumatic stress disorder (PTSD) as well as depression, headache and anxiety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to certain pyrazolo 4,3-d!pyrimidine derivativeswhich selectively bind to corticotropin-releasing factor (CRF)receptors. More specifically, the invention relates to 3-arylsubstituted pyrazolo 4,3-d!pyrimidine derivatives. The invention furtherrelates to pharmaceutical compositions comprising such compounds. Italso relates to the use of such compounds in treating stress relateddisorders such as post traumatic stress disorder (PTSD) as well asdepression, headache and anxiety.

2. Description of the Related Art

International Application PCT/US93/11333 describes pyrazolo3,4-d!pyrimidines said to be CRF antagonists. Bull. Chem. Soc. Japan.52(1), 208-11, (1979) describes the synthesis of 3-phenyl-pyrazolo4,3-d!pyrimidines.

SUMMARY OF THE INVENTION

This invention provides novel compounds of Formula I which interact withCRF receptors.

The invention provides pharmaceutical compositions comprising compoundsof Formula I. It further relates to the use of such compounds intreating stress related disorders such as post traumatic stress disorder(PTSD) as well as depression, headache and anxiety. Accordingly, a broadembodiment of the invention is directed to a compound of Formula I:##STR2## wherein Ar is phenyl, 1- or 2-naphthyl, 2-, 3-, or 4-pyridinyl,2- or 3-thienyl, 4- or 5-pyrimidinyl, each of which is mono-, di-, ortrisubstituted with halogen, hydroxy, lower alkyl, or lower alkoxy,provided that at least one of the positions on Ar ortho to the point ofattachment to the pyrazole ring is substituted;

R₁ is lower alkyl;

R₂ is hydrogen, halogen, lower alkyl, lower alkoxy, or thioalkoxy having1-6 carbon atoms;

R₃ and R₄ are the same or different and represent

hydrogen, lower alkyl, alkoxy lower alkyl, hydroxy lower alkyl, oralkenyl;

phenyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl or 2-, 4- or5-pyrimidinyl, each of which is optionally mono- or disubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy;

phenyl-, 2-, 3-, or 4-pyridinyl-, 2- or 3-thienyl-, or 2-, 4- or5-pyrimidinyl-lower alkyl, each of which is optionally mono- ordisubstituted with lower alkyl;

cycloalkyl or cycloalkyl lower alkyl, each of which is optionally mono-or disubstituted with lower alkyl; or

2-hydroxyethyl or 3-hydroxypropyl, each of which is optionallymonosubstituted with lower alkyl;

provided that not both R₃ and R₄ are hydrogen; or

R₃ and R₄ taken together represent --(CH₂)_(n) --A--(CH₂)_(m) -- where

n is 2, or 3;

A is methylene, 1,2-phenylene, oxygen, sulfur or NR₆, wherein R₆ islower alkyl, phenyl, 2-, 3-, or 4-pyridinyl, 2-or 3-thienyl or 2-, 4- or5-pyrimidinyl, or phenyl-, 2-, 3-or 4-pyridinyl-, 2-or 3-thienyl-, or2-, 4- or 5-pyrimidinylalkyl; and

m is 1, 2 or 3.

These compounds are highly selective partial agonists or antagonists atCRF receptors and are useful in the diagnosis and treatment of stressrelated disorders such as post traumatic stress disorder (PTSD) as wellas depression and anxiety.

DETAILED DESCRIPTION OF THE INVENTION

In addition to the compounds of Formula I above, the inventionencompasses of Formula II: ##STR3## wherein R_(a) represents halogen,hydroxy, lower alkyl, or lower alkoxy;

R_(b), and R_(c) independently represent hydrogen, halogen, hydroxy,lower alkyl, or lower alkoxy;

R₁ is lower alkyl;

R₂ is hydrogen or lower alkyl; and

R₃ and R₄ are the same or different and represent hydrogen, lower alkyl,lower alkenyl, cycloalkyl, cycloalkyl lower alkyl, 2-hydroxyethyl or3-hydroxypropyl;

provided that not both R₃ and R₄ are hydrogen.

Preferred compounds of Formula II are those where R₃ and R₄independently represent C₁ -C₆ alkyl (i.e., lower alkyl) optionallysubstituted with halogen, hydroxy, or C₁ -C₆ alkoxy, Ar is phenyl thatis mono-, di-, or trisubstituted with halogen, hydroxy, C₁ -C₆ alkyl, orC₁ -C₆ alkoxy, with the proviso that at least one of the positions onthe phenyl group ortho to the point of attachment to the pyrazole ringis substituted. More preferred compounds of Formula II are those whereAr is phenyl that is trisubstituted with C₁ -C₆ alkyl, with the provisothat at least one of the positions on the phenyl group ortho to thepoint of attachment to the pyrazole ring is substituted. Most preferredcompounds of Formula II are those where Ar is phenyl that istrisubstituted in the 2, 4, and 6 positions (para and both orthopositions relative to the point of attachment to the pyrazole ring) withC₁ -C₃ alkyl, most preferably methyl. Particularly preferred compoundsof Formula II are those where R₃ and R₄ are independently hydrogen or C₁-C₄ alkyl, e.g., methyl, ethyl, propyl, butyl, or cyclopropylmethyl,provided not both R₃ and R₄ are hydrogen.

The invention further encompasses compounds of Formula III: ##STR4##wherein R_(a) represents halogen, hydroxy, lower alkyl, or lower alkoxy;

R_(b), and R_(c) independently represent hydrogen, halogen, hydroxy,lower alkyl, or lower alkoxy;

R₁ is lower alkyl;

R₂ is hydrogen or lower alkyl; and

R₃ and R₄ are the same or different and represent

hydrogen, lower alkyl, cycloalkyl, cycloalkyl lower alkyl, or alkenyl;

phenyl, 2-, 3-, or 4-pyridinyl, or 2-, 4- or 5-pyrimidinyl, each ofwhich is optionally mono- or disubstituted with halogen, hydroxy, loweralkyl, or lower alkoxy; or

phenyl-, 2-, 3-, or 4-pyridinyl-, or 2-, 4- or 5-pyrimidinyl-loweralkyl, each of which is optionally mono- or disubstituted with loweralkyl;

provided that not both R₃ and R₄ are hydrogen.

Further, the invention encompasses compounds of Formula IV: ##STR5##wherein R_(a) represents halogen, hydroxy, lower alkyl, or lower alkoxy;

R_(b), and R_(c) independently represent hydrogen, halogen, hydroxy,lower alkyl, or lower alkoxy;

R₁ is lower alkyl;

R₂ is hydrogen or lower alkyl; and

R₃ and R₄ taken together represent with the nitrogen atom to which theyare attached represent --(CH₂)_(n) --A--(CH₂)_(m) -- where

n is 2, or 3;

A is methylene, 1,2-phenylene, oxygen, sulfur or NR₆, wherein R₆ islower alkyl, phenyl, 2-, 3-, or 4-pyridinyl, 2-or 3-thienyl or 2-, 4- or5-pyrimidinyl, or phenyl-, 2-, 3-or 4-pyridinyl-, 2-or 3-thienyl-, or2-, 4- or 5-pyrimidinylalkyl; and

m is 1, 2 or 3.

Preferred compounds of the invention have Formula V: ##STR6## whereinR_(a), R_(b), and R_(c) independently represent hydrogen, halogen,hydroxy, lower alkyl, or lower alkoxy, with the proviso that not bothR_(a) and R_(c) are hydrogen;

R₁ is lower alkyl;

R₂ is hydrogen or lower alkyl; and

R₃ and R₄ are the same or different and represent hydrogen, lower alkyl,cycloalkyl, cycloalkyl lower alkyl, alkenyl, 2-hydroxyethyl or3-hydroxypropyl, provided that not both R₃ and R₄ are hydrogen.

Other preferred compounds of Formula V are those where R₃ and R₄independently represent C₁ -C₆ alkyl (i.e., lower alkyl) optionallysubstituted with halogen, hydroxy, or C₁ -C₆ alkoxy.

More preferred compounds of Formula V are those where R_(a), R_(b), andR_(c) are methyl. Particularly preferred compounds of Formula V arethose where R_(a), R_(b), and R_(c) are methyl, R₁ and R₂ independentlyrepresent lower alkyl, and R₃ and R₄ are independently hydrogen or C₁-C₄ alkyl, e.g., methyl, ethyl, propyl, butyl, or cyclopropylmethyl,provided not both R₃ and R₄ are hydrogen.

Other preferred compounds of the invention have Formula VI: ##STR7##wherein R_(a), R_(b), and R_(c) independently represent hydrogen,halogen, hydroxy, lower alkyl, or lower alkoxy, with the proviso thatnot both R_(a) and R_(c) are hydrogen;

R₁ is lower

R₂ is hydrogen or lower alkyl; and

R₃ and R₄ are the same or different and represent hydrogen, lower alkyl,cycloalkyl, cycloalkyl lower alkyl, alkenyl, 2-hydroxyethyl or3-hydroxypropyl, provided that not both R₃ and R₄ are hydrogen.

Other preferred compounds of Formula VI are those where R₃ and R₄independently represent C₁ -C₆ alkyl (i.e., lower alkyl) optionallysubstituted with halogen, hydroxy, or C₁ -C₆ alkoxy.

More preferred compounds of Formula VI are those where R_(a), R_(b), andR_(c) are methyl. Particularly preferred compounds of Formula VI arethose where R_(a), R_(b), and R_(c) are methyl, R₁ and R₂ independentlyrepresent lower alkyl, and R₃ and R₄ are independently hydrogen or C₁-C₄ alkyl, e.g., methyl, ethyl, propyl, butyl, or cyclopropylmethyl,provided not both R₃ and R₄ are hydrogen.

The invention also encompasses intermediates for preparing compounds ofFormula I. Among these intermediates are compounds of Formula VII:##STR8## wherein R_(s) is hydrogen or lower alkyl;

R₁ and R₂ are as defined above for Formula I;

R_(a) is hydrogen or R_(b) O₂ C-- where R_(b) represents C₁ -C₆ alkyl;and

Ar is phenyl, 1- or 2-naphthyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl,4- or 5-pyrimidinyl, each of which is mono-, di-, or trisubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy, provided that at leastone of the positions on Ar ortho to the point of attachment to thepyrazole ring is substituted.

Preferred Ar groups are 2,4,6-tri(C₁ -C₆)alkylphenyl groups, mostpreferably 2,4,6-trimethylphenyl groups. Preferred R_(s) groups arehydrogen and methyl.

The invention further encompasses intermediates of Formula VIII:##STR9## wherein R₁ and R₂ are as defined above for Formula I;

R_(a) is hydrogen or R_(b) O₂ C-- where R_(b) represents C₁ -C₆ alkyl;and

Ar is phenyl, 1- or 2-naphthyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl,4- or 5-pyrimidinyl, each of which is mono-, di-, or trisubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy, provided that at leastone of the positions on Ar ortho to the point of attachment to thepyrazole ring is substituted.

Preferred Ar groups are 2,4,6-tri(C₁ -C₆)alkylphenyl groups, mostpreferably 2,4,6-trimethylphenyl groups.

The invention further encompasses intermediates of Formula IX: ##STR10##wherein R_(o) is hydrogen or lower alkyl;

R₁ and R₂ are as defined above for Formula I; and

Ar is phenyl, 1- or 2-naphthyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl,4- or 5-pyrimidinyl, each of which is mono-, di-, or trisubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy, provided that at leastone of the positions on Ar ortho to the point of attachment to thepyrazole ring is substituted.

Preferred Ar groups are 2,4,6-tri(C₁ -C₆)alkylphenyl groups, mostpreferably 2,4,6-trimethylphenyl groups. Preferred R_(o) groups aremethyl and ethyl.

Also, intermediates of Formula X are within the invention: ##STR11##wherein R_(o) is hydrogen or lower alkyl;

R₁ and R₂ are as defined above for Formula I; and

Ar is phenyl, 1- or 2-naphthyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl,4- or 5-pyrimidinyl, each of which is mono-, di-, or trisubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy, provided that at leastone of the positions on Ar ortho to the point of attachment to the alkyl2,4-dioxo-3-oximinobutanoate moiety is substituted.

Preferred Ar groups are 2,4,6-tri(C₁ -C₆)alkylphenyl groups, mostpreferably 2,4,6-trimethylphenyl groups. Preferred R_(o) groups aremethyl and ethyl.

The invention also encompasses compounds of Formula XI: ##STR12## whereR_(o) is hydrogen or lower alkyl;

R₁ and R₂ are as defined above for Formula I; and

Ar is phenyl, 1- or 2-naphthyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl,4- or 5-pyrimidinyl, each of which is mono-, di-, or trisubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy, provided that at leastone of the positions on Ar ortho to the point of attachment to thealkyl-2,4-dioxobutanoate moiety is substituted.

Preferred Ar groups are 2,4,6-tri(C₁ -C₆)alkylphenyl groups, mostpreferably 2,4,6-trimethylphenyl groups. Preferred R_(o) groups aremethyl and ethyl.

Representative compounds of the present invention, which are encompassedby Formula I, include, but are not limited to the compounds in Table Iand their pharmaceutically acceptable salts. Non-toxic pharmaceuticallyacceptable salts include salts of acids such as hydrochloric,phosphoric, hydrobromic, sulfuric, sulfinic, formic, toluenesulfonic,methanesulfonic, nitric, benzoic, citric, tartaric, maleic, hydroiodic,alkanoic such as acetic, HOOC--(CH₂)_(n) --COOH where n is 0-4, and thelike. Those skilled in the art will recognize a wide variety ofnon-toxic pharmaceutically acceptable addition salts.

The present invention also encompasses the acylated prodrugs of thecompounds of Formula I. Those skilled in the art will recognize varioussynthetic methodologies which may be employed to prepare non-toxicpharmaceutically acceptable addition salts and acylated prodrugs of thecompounds encompassed by Formula I.

When a compound of formula I is obtained as a mixture of enantiomersthese may be separated by conventional methods such as crystallizationin the presence of a resolving agent, or chromatography, for example,using a chiral HPLC column.

In the compounds of the invention, the Ar group is preferably a phenylgroup that is mono-, di-, or trisubstituted with halogen, hydroxy, C₁-C₆ alkyl, or C₁ -C₆ alkoxy, with the proviso that at least one of thepositions on the phenyl group ortho to the point of attachment to theisoquinolinamine or phthalazinamine ring is substituted. Where Ar isphenyl, the carbon atom by which the phenyl group is attached to thepyrazole ring is defined as the 1-position. Thus, the positions ortho tothe point of attachment are the 2 and 6 positions, and the para positionis the 4-position of the phenyl group.

By the terms (C₁ -C₆)alkyl and lower alkyl is meant straight andbranched chain alkyl groups having from 1-6 carbon atoms as well ascyclic alkyl groups such as, for example, cyclopropyl, cyclobutyl, orcyclohexyl. Specific examples of such alkyl groups are methyl, ethyl,propyl, isopropyl, n-butyl, isobutyl, tert-butyl, sec-butyl, neopentyland n-pentyl. Preferred C₁ -C₆ alkyl groups are methyl, ethyl, propyl,butyl or cyclopropylmethyl.

By the terms (C₁ -C₆)alkoxy and lower alkoxy is meant straight andbranched chain alkoxy groups having from 1-6 carbon atoms.

By hydroxy C₁ -C₆ alkyl or hydroxyalkyl is meant a C₁ -C₆ alkyl groupcarrying a terminal hydroxy moiety.

By C₁ -C₆ alkoxy C₁ -C₆ alkyl (alkoxy lower alkyl) is meant a group ofthe formula --(CH₂)_(x) O(CH₂)_(y) CH₃, where x and y independentlyrepresent integers of from 1-6.

By the term C₁ -C₆ alkenyl or lower alkenyl is meant straight orbranched chain hydrocarbon groups having from 1-6 carbon atoms and atleast one double bond.

By halogen, halo, or halide is meant fluorine, chlorine, bromine andiodine substituents.

By aryl(C₁ -C₆)alkyl, e.g., phenylalkyl, pyridinylalkyl,pyrimidinylalkyl, and thienylalkyl, is meant aryl groups attached to theparent group by a straight or branched chain alkyl group having 1-6carbon atoms. Thus, the aryl groups include phenyl, 1- or 2-naphthyl,2-, 3-, or 4-pyridinyl, 2- or 3-thienyl or 2-, 4-, or 5-pyrimidinyl.These aryl groups are optionally substituted with up to two groupsselected from halogen, hydroxy, (C₁ -C₆)alkyl, and (C₁ -C₆)alkoxy.

Representative examples of compounds according to the invention areshown in Table 1 below. ##STR13##

The pharmaceutical utility of compounds of this invention is indicatedby the following assay for CRF receptor activity.

Assay for CRF receptor binding activity

CRF receptor binding is performed using a modified version of the assaydescribed by Grigoriadis and De Souza (Biochemical, Pharmacological, andAutoradiographic Methods to Study Corticotropin-Releasing FactorReceptors. Methods in Neurosciences, Vol. 5, 1991). Membrane pelletscontaining CRF receptors are resuspended in 50 mM Tris buffer pH 7.7containing 10 mM MgCl₂ and 2 mM EGTA and centrifuged for 10 minutes at48000 g. Membranes are washed again and brought to a final concentrationof 1500 μg/ml in binding buffer (Tris buffer described above with 0.1%BSA, 0.15 mM bacitracin and 0.01 mg/ml aprotinin.). For the bindingassay, 100 μl of the membrane preparation is added to 96-well microtubeplates containing 100 μl of ¹²⁵ I-CRF (SA 2200 Ci/mmol, finalconcentration of 100 pM) and 50 μl of drug. Binding is carried out atroom temperature for 2 hours. Plates are then harvested on a Brandel 96well cell harvester and filters are counted for gamma emissions on aWallac 1205 Betaplate liquid scintillation counter. Non specific bindingis defined by 1 uM cold CRF. IC₅₀ values are calculated with thenon-linear curve fitting program RS/1 (BBN Software Products Corp.,Cambridge, Mass.). The compounds of the invention typically have bindingaffinities, expressed as IC₅₀ values, of from about 0.5 nanomolar (nM)to about 10 micromolar (μM). The binding characteristics forrepresentative examples of the invention are shown in Table 1.

                  TABLE I                                                         ______________________________________                                        Compound Number  IC.sub.50 (nM)                                               ______________________________________                                        1                1.4                                                          3                1.8                                                          ______________________________________                                    

Compound numbers relate to compounds described in the examples below:

The compounds of general formula I may be administered orally,topically, parenterally, by inhalation or spray or rectally in dosageunit formulations containing conventional non-toxic pharmaceuticallyacceptable carriers, adjuvants and vehicles. The term parenteral as usedherein includes subcutaneous injections, intravenous, intramuscular,intrasternal injection or infusion techniques. In addition, there isprovided a pharmaceutical formulation comprising a compound of generalformula I and a pharmaceutically acceptable carrier. One or morecompounds of general formula I may be present in association with one ormore non-toxic pharmaceutically acceptable carriers and/or diluentsand/or adjuvants and if desired other active ingredients. Thepharmaceutical compositions containing compounds of general formula Imay be in a form suitable for oral use, for example, as tablets,troches, lozenges, aqueous or oily suspensions, dispersible powders orgranules, emulsion, hard or soft capsules, or syrups or elixirs.

Compositions intended for oral use may be prepared according to anymethod known to the art for the manufacture of pharmaceuticalcompositions and such compositions may contain one or more agentsselected from the group consisting of sweetening agents, flavoringagents, coloring agents and preserving agents in order to providepharmaceutically elegant and palatable preparations. Tablets contain theactive ingredient in admixture with non-toxic pharmaceuticallyacceptable excipients which are suitable for the manufacture of tablets.These excipients may be for example, inert diluents, such as calciumcarbonate, sodium carbonate, lactose, calcium phosphate or sodiumphosphate; granulating and disintegrating agents, for example, cornstarch, or alginic acid; binding agents, for example starch, gelatin oracacia, and lubricating agents, for example magnesium stearate, stearicacid or talc. The tablets may be uncoated or they may be coated by knowntechniques to delay disintegration and absorption in thegastrointestinal tract and thereby provide a sustained action over alonger period. For example, a time delay material such as glycerylmonostearate or glyceryl distearate may be employed.

Formulations for oral use may also be presented as hard gelatin capsuleswherein the active ingredient is mixed with an inert solid diluent, forexample, calcium carbonate, calcium phosphate or kaolin, or as softgelatin capsules wherein the active ingredient is mixed with water or anoil medium, for example peanut oil, liquid paraffin or olive oil.

Aqueous suspensions contain the active materials in admixture withexcipients suitable for the manufacture of aqueous suspensions. Suchexcipients are suspending agents, for example sodiumcarboxymethylcellulose, methylcellulose, hydropropylmethylcellulose,sodium alginate, polyvinylpyrrolidone, gum tragacanth and gum acacia;dispersing or wetting agents may be a naturally-occurring phosphatide,for example, lecithin, or condensation products of an alkylene oxidewith fatty acids, for example polyoxyethylene stearate, or condensationproducts of ethylene oxide with long chain aliphatic alcohols, forexample heptadecaethyleneoxycetanol, or condensation products ofethylene oxide with partial esters derived from fatty acids and ahexitol such as polyoxyethylene sorbitol monooleate, or condensationproducts of ethylene oxide with partial esters derived from fatty acidsand hexitol anhydrides, for example polyethylene sorbitan monooleate.The aqueous suspensions may also contain one or more preservatives, forexample ethyl, or n-propyl p-hydroxybenzoate, one or more coloringagents, one or more flavoring agents, and one or more sweetening agents,such as sucrose or saccharin.

Oily suspensions may be formulated by suspending the active ingredientsin a vegetable oil, for example arachis oil, olive oil, sesame oil orcoconut oil, or in a mineral oil such as liquid paraffin. The oilysuspensions may contain a thickening agent, for example beeswax, hardparaffin or cetyl alcohol. Sweetening agents such as those set forthabove, and flavoring agents may be added to provide palatable oralpreparations. These compositions may be preserved by the addition of ananti-oxidant such as ascorbic acid.

Dispersible powders and granules suitable for preparation of an aqueoussuspension by the addition of water provide the active ingredient inadmixture with a dispersing or wetting agent, suspending agent and oneor more preservatives. Suitable dispersing or wetting agents andsuspending agents are exemplified by those already mentioned above.Additional excipients, for example sweetening, flavoring and coloringagents, may also be present.

Pharmaceutical compositions of the invention may also be in the form ofoil-in-water emulsions. The oily phase may be a vegetable oil, forexample olive oil or arachis oil, or a mineral oil, for example liquidparaffin or mixtures of these. Suitable emulsifying agents may benaturally-occurring gums, for example gum acacia or gum tragacanth,naturally-occurring phosphatides, for example soy bean, lecithin, andesters or partial esters derived from fatty acids and hexitol,anhydrides, for example sorbitan monooleate, and condensation productsof the said partial esters with ethylene oxide, for examplepolyoxyethylene sorbitan monooleate. The emulsions may also containsweetening and flavoring agents.

Syrups and elixirs may be formulated with sweetening agents, for exampleglycerol, propylene glycol, sorbitol or sucrose. Such formulations mayalso contain a demulcent, a preservative and flavoring and coloringagents. The pharmaceutical compositions may be in the form of a sterileinjectable aqueous or oleaginous suspension. This suspension may beformulated according to the known art using those suitable dispersing orwetting agents and suspending agents which have been mentioned above.The sterile injectable preparation may also be sterile injectablesolution or suspension in a non-toxic parentally acceptable diluent orsolvent, for example as a solution in 1,3-butanediol. Among theacceptable vehicles and solvents that may be employed are water,Ringer's solution and isotonic sodium chloride solution. In addition,sterile, fixed oils are conventionally employed as a solvent orsuspending medium. For this purpose any bland fixed oil may be employedincluding synthetic mono-or diglycerides. In addition, fatty acids suchas oleic acid find use in the preparation of injectables.

The compounds of general formula I may also be administered in the formof suppositories for rectal administration of the drug. Thesecompositions can be prepared by mixing the drug with a suitablenon-irritating excipient which is solid at ordinary temperatures butliquid at the rectal temperature and will therefore melt in the rectumto release the drug. Such materials are cocoa butter and polyethyleneglycols.

Compounds of general formula I may be administered parenterally in asterile medium. The drug, depending on the vehicle and concentrationused, can either be suspended or dissolved in the vehicle.Advantageously, adjuvants such as local anesthetics, preservatives andbuffering agents can be dissolved in the vehicle.

Dosage levels of the order of from about 0.1 mg to about 140 mg perkilogram of body weight per day are useful in the treatment of theabove-indicated conditions (about 0.5 mg to about 7 g per patient perday). The amount of active ingredient that may be combined with thecarrier materials to produce a single dosage form will vary dependingupon the host treated and the particular mode of administration. Dosageunit forms will generally contain between from about 1 mg to about 500mg of an active ingredient.

It will be understood, however, that the specific dose level for anyparticular patient will depend upon a variety of factors including theactivity of the specific compound employed, the age, body weight,general health, sex, diet, time of administration, route ofadministration, and rate of excretion, drug combination and the severityof the particular disease undergoing therapy.

A representative illustration of methods suitable for the preparation ofcompounds of the present invention is shown in Scheme I. Those havingskill in the art will recognize that the starting materials may bevaried and additional steps employed to produce compounds encompassed bythe present invention. For example, in certain situations, protection ofreactive moieties such as amino groups will be required. ##STR14##

In the above scheme, R₁ -R₄, and Ar carry the definitions set forthabove for Formula I.

The disclosures in this application of all articles and references,including patents, are incorporated herein by reference.

The invention is illustrated further by the following examples which arenot to be construed as limiting the invention in scope or spirit to thespecific procedures and compounds described in them.

EXAMPLE 1 A. Ethyl 2,4-dioxo-4-(2,4,6-trimethylphenyl)butanoate##STR15##

To a solution of 2', 4', 6'-trimethylacetophenone (15 g, 92.6 mmol) anddiethyl oxalate (20 g, 139 mmol) in 500 mL of anhydrous toluene wascautiously added 7.4 g of NaH (60% dispersion in mineral oil). Thereaction mixture was slowly heated to reflux under N₂. It was refluxedfor about 20 minutes, then cooled, poured into ice-cold aqueous HClsolution, and extracted with ether. The extracts were washed with brine,dried over Na₂ SO₄, filtered through a short silica gel pad andconcentrated to give 16.2 g of a red oil which was used in the nextreaction without further purification.

B. Ethyl 2,4-dioxo-3-oximino-4-(2,4,6-trimethylphenyl)butanoate##STR16##

N₂ O₃ gas was slowly passed into a stirred solution of the product ofstep A (16.2 g) in 300 mL of ethanol until the disappearance of startingmaterial was confirmed by TLC. N₂ O₃ gas was generated by the dropwiseaddition of 12N aqueous HCl solution into an aqueous slurry of NaNO₂.The solvent was removed from the mixture and 200 mL of water was addedto the residue. The product was then extracted into ether. The etherextract was dried over Na₂ SO₄ and evaporated to give 16.1 g of asemi-solid.

C. Ethyl4-amino-1-methyl-5-(2,4,6-trimethylphenyl)pyrazole-3-carboxylate##STR17##

To a solution of the product of step B (4.0 g, 13.8 mmol) and 1.6 mL of12N hydrochloric acid in 100 mL of methanol was added dropwise 0.63 g ofmethyl hydrazine at 0° C. The reaction mixture was stirred at roomtemperature 4 hours, and then concentrated. The resulting residue waspartitioned between water and ethyl acetate. The organic phase wasseparated and washed once with brine. The ethyl acetate solution wasthen mixed with 100 mL of water. Solid Na₂ S₂ O₄ in excess was added insmall portion until TLC showed completion of the reduction. The organicphase was separated, washed with water and brine, and dried over Na₂SO₄. Evaporation gave 3.1 g of the title compound as a foam.

D. 2,5-Dimethyl-3-(2,4,6-trimethylphenyl)-2,6-dihydro-2H-pyrazolo4,3-d!pyrimidin-7-one ##STR18##

A solution of the product of step C (3.1 g) in 100 mL of anhydrous CH₃CN was saturated with HCl gas, stirred at room temperature overnight,and then concentrated. The residue was partitioned between aqueousNaHCO₃ solution and ethyl acetate. The organic layer was separated,washed with brine, dried over Na₂ SO₄ and concentrated. The residue wastriturated with ether. The solid was collected by filtration to give 1.0g of the title compound as a white solid, m.p. 264°-66° C.

E. 2,5-Dimethyl-3-(2,4,6-trimethylphenyl)-2,4-dihydro-2H-pyrazolo4,3-d!pyrimidin-7-thione ##STR19##

A mixture of the product of step D (0.6 g, 2.2 mmol) and P₂ S₅ (1.0 g,2.2 mmol) in 50 mL of dioxane was heated to reflux for 2 hours. Thesolvent was evaporated. The residue was partitioned between water andethyl acetate. The organic layer was separated, washed with brine, driedover Na₂ SO₄ and concentrated to give 0.60 g of the title compound as ayellow foam.

F. N-Propyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine ##STR20##

A solution of the product of step E (0.6 g) and 1 mL of propylamine in10 mL of ethanol was heated to reflux for 3 hours. Evaporation of thevolatile gave 550 mg of the title compound as a foam.

G. N,N-Dipropyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine (Compound 1) ##STR21##

A mixture of the product of step F (400 mg, 1.2 mmol), powder KOH (1.0g) and 1-bromopropane (1 mL) in 2 mL of DMSO was heated at 60° C. for 8hours. The excess bromopropane was then evaporated. The mixture waspartitioned between water and ether. The aqueous layer was separated andextracted with ether. The combined ether extracts were washed with waterand brine, dried over Na₂ SO₄ and concentrated to an oil. The oil waspurified through silica gel column chromatography to give 260 mg of thetitle compound as an oil. ¹ H NMR (CDCl₃): d 0.97 (t, 6H), 1.76 (m, 4H),1.96 (s, 6H), 2.32 (s, 3H), 2.45 (s, 3H), 3.77 (s, 3H), 3.40-4.30 (br,4H), 6.95 (s, 2H)ppm. The hydrochloride salt prepared in Ether/HClmelted at 210°-13° C.

EXAMPLE 2 AND EXAMPLE 3 A.N-Ethyl-5-methyl-3-(2,4,6-trimethylphenyl)-1H-pyrazolo4,3-d!pyrimidin-7-amine ##STR22##

A solution of 5-Methyl-3-(2,4,6-trimethylphenyl)-1H-pyrazolo4,3-d!pyrimidin-7-thione (250 mg, prepared in a manner similar to thecompound of step E in Example 1) and 25 mL of ethylamine (2M inmethanol) was heated to reflux for 3 hours. Evaporation of the volatilegave 255 mg of the title compound as a foam.

B. 1. N,N-Diethyl-1-ethyl-5-methyl-3-(2,4,6-trimethylphenyl)-1H-pyrazolo4,3-d!pyrimidin-7-amine (Example 2) (Compound 2) ##STR23## 2.N,N-Diethyl-2-ethyl-5-methyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pydmidin-7-amine (Example 3) ##STR24##

A mixture of the product of step A (250 mg, 0.85 mmol), powdered KOH(0.5 mg) and 1-bromopropane (0.5 mL) in 2 mL of DMSO was heated at 60°C. for 2 hours. The excess bromopropane was then evaporated. The mixturewas partitioned between water and ether. The aqueous layer was separatedand extracted with ether. The combined ether extracts were washed withwater and brine, dried over Na₂ SO₄ and concentrated to an oil. The oilwas purified through silica gel column chromatography using Hexane/EtOAc(100/30, v/v). The faster moving fraction, comprising the titledcompound (example 2) was collected. Evaporation of the solvents gave 26mg of the title compound (example 2) as an oil. ¹ H NMR (CDCl₃): d 1.24(t, 6H), 1.37 (t, 3H), 2.08 (s, 6H), 2.31 (s, 3H), 2.60 (s, 3H), 3.58(q, 4H), 4.44 (q, 2H), 6.94 (s, 2H)ppm. The slower moving fraction,comprising the titled compound (example 3) was collected. Evaporation ofthe solvents gave 80 mg of the title compound (example 3) as an oil. ¹ HNMR (CDCl₃): d 1.32 (t, 6H), 1.36 (t, 3H), 1.98 (s, 6H), 2.33 (s, 3H),2.47 (s, 3H), 4.03 (q, 2H), 3.60-4.40 (br, 4H), 6.97 (s, 2H)ppm.

The following compounds are prepared essentially according to proceduresset forth above in Examples 1, 2, and 3.

EXAMPLE 4

N-Cyclopropylmethyl-N-propyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo 4,3-d!pyrimidin-7-amine (Compound 3).

EXAMPLE 5

N-Ethyl-N-propyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

EXAMPLE 6

N-Butyl-N-ethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

EXAMPLE 7

N,N-Diethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

EXAMPLE 8

N,N-Diallyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

EXAMPLE 9

N-Ethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

EXAMPLE 10

7-(1-Morpholino)-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidine.

EXAMPLE 11

N-Benzyl-N-ethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

EXAMPLE 12

N,N-Di1-(2-methoxy)ethyl!-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.

The invention and the manner and process of making and using it, are nowdescribed in such full, clear, concise and exact terms as to enable anyperson skilled in the art to which it pertains, to make and use thesame. It is to be understood that the foregoing describes preferredembodiments of the present invention and that modifications may be madetherein without departing from the spirit or scope of the presentinvention as set forth in the claims. To particularly point out anddistinctly claim the subject matter regarded as invention, the followingclaims conclude this specification.

What is claimed is:
 1. A compound of the formula: ##STR25## or thepharmaceutically acceptable salts thereof wherein Ar is phenyl, 1- or2-naphthyl, 2-, 3-, or 4-pyridinyl, 2- or 3-thienyl, 4- or5-pyrimidinyl, each of which is mono-, di-, or trisubstituted withhalogen, hydroxy, lower alkyl, or lower alkoxy, provided that at leastone of the positions on Ar ortho to the point of attachment to thepyrazole ring is substituted;R₁ is lower alkyl; R₂ is hydrogen, halogen,lower alkyl, lower alkoxy, or thioalkoxy having 1-6 carbon atoms; R₃ andR₄ are the same or different and representhydrogen, lower alkyl, alkoxylower alkyl, hydroxy lower alkyl, or alkenyl; phenyl, 2-, 3-, or4-pyridinyl, 2- or 3-thienyl or 2-, 4- or 5-pyrimidinyl, each of whichis optionally mono- or disubstituted with halogen, hydroxy, lower alkyl,or lower alkoxy; phenyl-, 2-, 3-, or 4-pyridinyl-, 2- or 3-thienyl-, or2-, 4- or 5-pyrimidinyl-lower alkyl, each of which is optionally mono-or disubstituted with lower alkyl; cycloalkyl or cycloalkyl lower alkyl,each of which is optionally mono- or disubstituted with lower alkyl; or2-hydroxyethyl or 3-hydroxypropyl, each of which is optionallymonosubstituted with lower alkyl;provided that not both R₃ and R₄ arehydrogen; or R₃ and R₄ taken together represent --(CH₂)_(n)--A--(CH₂)_(m) -- wheren is 2, or 3; A is methylene, 1,2-phenylene,oxygen, sulfur or NR₆, wherein R₆ is lower alkyl, phenyl, 2-, 3-, or4-pyridinyl, 2-or 3-thienyl or 2-, 4- or 5-pyrimidinyl, or phenyl, 2-,3-or 4-pyridinyl-, 2-or 3-thienyl-, or 2-, 4- or 5-pyrimidinylalkyl; andm is 1, 2or
 3. 2. A compound of the formula: ##STR26## or thepharmaceutically acceptable salts thereof wherein R_(a) representshalogen, hydroxy, lower alkyl, or lower alkoxy;R_(b), and R_(c)independently represent hydrogen, halogen, hydroxy, lower alkyl, orlower alkoxy; R₁ is lower alkyl; R₂ is hydrogen or lower alkyl; and R₃and R₄ are the same or different and represent hydrogen, lower alkyl,lower alkenyl, cycloalkyl, cycloalkyl lower alkyl, 2-hydroxyethyl or3-hydroxypropyl;provided that not both R₃ and R₄ are hydrogen.
 3. Acompound of the formula: ##STR27## or the pharmaceutically acceptablesalts thereof wherein R_(a) represents halogen, hydroxy, lower alkyl, orlower alkoxy;R_(b), and R_(c) independently represent hydrogen halogen,hydroxy, lower alkyl, or lower alkoxy; R₁ is lower alkyl; R₂ is hydrogenor lower alkyl; and R₃ and R₄ are the same or different andrepresenthydrogen, lower alkyl, cycloalkyl, cycloalkyl lower alkyl, oralkenyl; phenyl, 2-, 3-, or 4-pyridinyl, or 2-, 4- or 5-pyrimidinyl,each of which is optionally mono- or disubstituted with halogen,hydroxy, lower alkyl, or lower alkoxy; or phenyl-, 2-, 3-, or4-pyridinyl-, or 2-, 4- or 5-pyrimidinyl-lower alkyl, each of which isoptionally mono- or disubstituted with lower alkyl;provided that notboth R₃ and R₄ are hydrogen.
 4. A compound of the formula: ##STR28## orthe pharmaceutically acceptable salts thereof wherein R_(a) representshalogen, hydroxy, lower alkyl, or lower alkoxy;R_(b), and R_(c)independently represent hydrogen halogen, hydroxy, lower alkyl, or loweralkoxy; R₁ is lower alkyl; R₂ is hydrogen or lower alkyl; and R₃ and R₄taken together represent with the nitrogen atom to which they areattached represent --(CH₂)_(n) --A--(CH₂)_(m) -- wheren is 2, or 3; A ismethylene, 1,2-phenylene, oxygen, sulfur or NR₆, wherein R₆ is loweralkyl, phenyl, 2-, 3-, or 4-pyridinyl, 2-or 3-thienyl or 2-, 4- or5-pyrimidinyl, or phenyl-, 2-, 3-or 4-pyridinyl-, 2-or 3-thienyl-, or2-, 4- or 5-pyrimidinylalkyl; and m is 1, 2 or
 3. 5. A compound of theformula: ##STR29## or the pharmaceutically acceptable salts thereofwherein R_(a), R_(b), and R_(c) independently represent hydrogen,halogen, hydroxy, lower alkyl, or lower alkoxy, with the proviso thatnot both R_(a) and R_(c) are hydrogen;R₁ is lower alkyl; R₂ is hydrogenor lower alkyl; and R₃ and R₄ are the same or different and representhydrogen, lower alkyl, cycloalkyl, cycloalkyl lower alkyl, alkenyl,2-hydroxyethyl or 3-hydroxypropyl, provided that not both R₃ and R₄ arehydrogen.
 6. A compound according to claim 5, wherein R_(a), R_(b), andR_(c) are methyl.
 7. A compound according to claim 6, wherein R₁ and R₂independently represent lower alkyl.
 8. A compound of the formula:##STR30## or the pharmaceutically acceptable salts thereof whereinR_(a), R_(b), and R_(c) independently represent hydrogen, halogen,hydroxy, lower alkyl, or lower alkoxy, with the proviso that not bothR_(a) and R_(c) are hydrogen;R₁ is lower alkyl; R₂ is hydrogen or loweralkyl; and R₃ and R₄ are the same or different and represent hydrogen,lower alkyl, cycloalkyl, cycloalkyl lower alkyl, alkenyl, 2-hydroxyethylor 3-hydroxypropyl, provided that not both R₃ and R₄ are hydrogen.
 9. Acompound according to claim 8, wherein R_(a), R_(b), and R_(c) aremethyl.
 10. A compound according to claim 9, wherein R₁ and R₂independently represent lower alkyl.
 11. A compound according to claim 1which is N,N-Dipropyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 12. A compound according to claim 1 which isN,N-Diethyl-1-ethyl-5-methyl-3-(2,4,6-trimethylphenyl)-1H-pyrazolo4,3-d!pyrimidin-7-amine.
 13. A compound according to claim 1 which isN,N-Diethyl-2-ethyl-5-methyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 14. A compound according to claim 1 which isN-Cyclopropylmethyl-N-propyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 15. A compound according to claim 1 which isN-Ethyl-N-propyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 16. A compound according to claim 1 which isN-Butyl-N-ethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 17. A compound according to claim 1 which isN,N-Diethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 18. A compound according to claim 1 which isN,N-Diallyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 19. A compound according to claim 1 which isN-Ethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 20. A compound according to claim 1 which is7-(1-Morpholino)-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidine.
 21. A compound according to claim 1 which isN-Benzyl-N-ethyl-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.
 22. A compound according to claim 1 which isN,N-Di1-(2-methoxy)ethyl!-2,5-dimethyl-3-(2,4,6-trimethylphenyl)-2H-pyrazolo4,3-d!pyrimidin-7-amine.